The first time that I heard of this movie was on Bravo's 100 scariest movie moments list. I've started to collect many of those movies and since Black Sunday is a vampire film (rather high on the list too), it was one of the first ones that I ordered.
Black Sunday is an incredible black and white film which DEFINITELY ranks up there with Bela Lugosi's "Dracula" and the (1922) "Nosferatu". Never before have I been frightened by the ATMOSPHERE that is found in a movie. This is exactly what Black Sunday does. The atmosphere is so haunting, so seemingly tangible - that it becomes one of the main characters in the movie. Director Mario Bava created a horror (not just vampire) film masterpiece. Not surprisingly, it is his best film.
Princess Asa is one of the most sensual vampires that I have seen and her ability to drain the life force from her victims is truly horrifying. An incredible film that MUST be watched, if not owned. I definitely recommend watching this old style vampire-horror film.